This invention relates to the production of thin films of semiconductor material having a high degree of surface uniformity, and more particularly relates to a process involving ion implantation into a body of semiconductor material to form a thin surface region defined by a buried region of high stress, followed by heating to separate the thin region from the body of the semiconductor material.
In U.S. Pat. No. 5,374,564, incorporated herein by reference, a process is described for the production of thin films of semiconductor material having a high degree of surface uniformity. The process has three stages: first, implantion of ions of hydrogen or a rare gas to form a buried region of high stress in a body of semiconductor material to define a thin surface region; second, attaching a stiffener to the surface of the thin region; and third, heating the semiconductor body to separate the thin region from the body. The patent teaches that the implantation must take place at a temperature below 500 degrees C., eg., between 20 and 450 degrees C., while heating to achieve separation must take place above 500 degrees C.
A potential use for such an "exfoliation" process is in the formation of silicon-on-insulator (SOI) substrates for high voltage semiconductor devices. Other potential uses, such as the removal of a thin layer of semiconductor material from a localized region of a partially completed semiconductor device or attachment to a glass carrier, are generally not feasible due to the heat treatment temperature required for separation.